Determinants of dropout in a longitudinal, cohort study of urologic disease in community-based men

Purpose To determine factors associated with dropout in a 12-year community-based, prospective cohort study of urologic disease in men. Methods During 1989 to 1991, 2115 randomly selected Caucasian men from Olmsted County, Minnesota, age 40 to 79 years, were enrolled in a study of benign prostatic hyperplasia (BPH) and followed with questionnaires biennially; 332 men were added in follow-up. A subset of men (not, vert, similar25%) received a urologic examination. Associations were evaluated between dropout as of the seventh biennial follow-up. Baseline characteristics included age, BPH (urinary symptoms and flow rate), prostate-specific antigen (PSA), prostate volume, comorbidities (hypertension, diabetes, stroke, coronary heart disease), and socioeconomic factors (marital status, education level). Results Of the 2447 men who began the study, 195 died between contacts and 682 did not participate in 2002. After excluding those who died, age was a dropout factor, with men 70 years of age or older at baseline being less likely to participate than men in the 40- to 49-year age group (odds ratio OR = 2.65; 95% confidence interval CI = 1.93, 3.63). Men who had suffered a stroke at baseline had the highest dropout, compared with men who had not suffered a stroke (age-adjusted OR = 3.07; CI = 1.49, 6.33); however, this represented a small percentage of the cohort, with 22 men who suffered a stroke at baseline dropping out. Presence of at least one BPH symptom was not a dropout factor (age-adjusted OR = 1.12; CI = 0.93, 1.36). Furthermore, individuals without a high school education were more likely to drop out than those with at least a high school education (age-adjusted OR = 2.50; CI = 1.80, 3.47). Conclusion These results provide some assurances that dropout was not related to primary study outcomes; however, factors such as comorbidities, age, and education level seem to play a role.